DESCRIPTION: Heart disease continues to be the number one killer in the United States, with over 25% of all deaths related to coronary artery disease (CAD). Morbidity and mortality in CAD has long been recognized to be directly related to the extent and the severity of coronary obstruction and the amount of myocardium at risk of infarction. Coronary arteriography and more recently intravascular ultrasound (IVUS) provide anatomic information and are used as the "gold standard" for the assessment of atheromatous obstruction. Emission tomography using single photon (SPECT) or positron emitting radionuclides (PET) provides physiologic information and is used as the clinical "gold standard" for the assessment of regional hypoperfusion and hypometabolism. EKG-synchronized emission tomography has also been valuable in assessing the extent of myocardial dysfunction. Accurate assessment of the extent and severity of CAD requires the multidimensional integration of anatomic and physiologic information obtained independently from these cardiac imaging modalities. However, integration has traditionally been subjective, time consuming, lacking standardization and difficult to conceptualize. The long term objective of the proposed research is to continue to develop and validate computer-based methods for the multidimensional quantification, unification and visualization of complementary, multi-modality cardiac images of coronary anatomy and myocardial perfusion, metabolism and function. Specifically, the aims of the proposed research consist of development, automation and validation of each of the following 4D (x,y,z,t) methodologies: 1) extension of the biplane reconstruction of the coronary vasculature to use two non-simultaneous single projections, to fuse the arterial tree with IVUS, and to optimize the arteriographic procedure through computer guidance of the gantry, 2) extension of the data-based approach to quantify myocardial perfusion, metabolism and function using EKG-gated PET and SPECT and from this information determine the area at risk, and 3) complete the registration and visualization of the coronary vasculature and myocardial perfusion, metabolism and function for a unified, comprehensive assessment of coronary artery disease and determination of amount of myocardium at risk of infarction.